Telephone system



June l1, 1940. E WQCHlNGER 2,203,935

TELEPHONE v SYSTEM Filed ot. 27 1937 EDUARD WOCHINGER ATTORNEY.

Patented June 1l, 1940 y :PATENT OFFICE TELEPHONE SYSTEM Eduard Wochinger, Berlin, Germany, assigner to Siemens & Halske Aktiengesellschaft,Wernerwerk, Semensstadt near Berlin, Germany` Application October .27,` 1937, Serial No. 171,203

In Germany November 6, 1936 i `12 Claims. (c1.` 179-26) `The present invention relatesto a circuit arrangement for semi-automatic telephone systems such" as are used for` example in localand toll systems in which automatic exchanges with central battery feeding are associated with small `local battery rural exchanges. VIn such systems calls from subscribers of the automatic exchanges are set up completely automatically, `while calls i `from subscribers of the local battery rural exchangesare set up with the aid of an operator.

In the case of calls offthe last type various switching operations such as ringing, setting of switches, and release are transmitted back over i the established connecting path. Since the ccn- 15 `necting path passes over a plurality of connecting y `lines coupled by repeaters the` switching operations are transmitted for the most part by the same Signals, i. e., short alternating current `impulses over the connecting lines` and short direct current impulses within the exchanges. The switching operations are differentiated in the receiving connecting devices in that different receiving relays are provided for receiving the y impulses in dependence upon the stage reached lin the establishment of the call. Now it may happen that in aconnecting device a switching measure taken on the part of the operator, e. g., ringing, coincides with a switching measure in theopposite direction on the part of the calling subscriber. In accordance with the stage reached in `the establishment of the call the signal transmitted by the subscriber tends tolead the impulses from theoperator to a receivingrelay which is not that provided for the switching operation occurring at that time. The impulses i from the operator thus promote a false switching y "operation, such as the false setting of switches. The inventionjaims at avoiding this diniculty in that twoA simultaneous signals arriving at a connecting device from opposite directions in` fluence separate receiving relays While auxiliary relays are provided which are iniiuenced partly from one of the receiving relays in such `a manner that the switchingcver of the receiving cir- 45 cuit of the counter-direction by one of,` the receiving relays on a third receivingerelay only takes place after the termination of the signal proceeding from the counterdirect`ion-- Theattached drawing represents one embodi- 50ment of the invention. i

Fig. 1 is a diagrammatic representation of a `local and toll System Withautomatic exchanges B, C and D and a local battery rural exchange A. Fig. 2 shows the relevant details ofthe repeater 55 Uel inthe exchange` B. In additionwthere is shown the secondary switch MW with its wipers am, bm, and cm and the testing relay PI and also the impulse contact 3111.2` of the repeating relay in the repeater U62. I

Referring now to Fig. 1, the general operation 5 of the system willbe explained. Calls which are set up from Subscribers of the automatic exchange B, l,C and D proceed `automatically while calls Which are set up from` subscribers of the rural exchange A are set up with the aid of an 10 operator whose position VPL is disposed in the exchange D. If a subscriber of the exchange A, for example subscriber Tnl, desires to set up a i call to subscriber TM of the automatic exchange B the following switching operations occur: 15

Subscriber Tnl operates a magneto with which every subscribers station of the exchange `A is provided and thereby starts `up the call iinder AS which sets itself onthe calling line. Whenthis `has occurred lthe connecting switch AW is set 20 `automatically on the call finder AS. The repeaterUel in exch'angeB is seized over the connecting line VL`|` by the connecting switch` AW.

This automatically starts upa secondary switch MWwhich` becomes set on `a free alternating 25 `current repeater Ue2. The alternating `current repeater Ue3 in the exchange C is seized by the y repeater UeZ over the connecting line VLfi. This repeater has access to a rst group selector GWG.

The first group selector GWc is raised to the rst 30 level by an impulse automatically` transmitted from the repeater Uel. It rotates freely search-` ingfor a free alternating current repeater Ue. From the repeater Ue an incoming alternating current repeater Uel l is reached in the exchange 35 D over the connecting line VLE. The repeater Uell has access toa second group 'selector GWd. Thegroup selector GWd is then raised to the second `level by two impulses whichI are transmitted automatically from the repeater Uel.` It hunts o over this leveland seizes a free exchange position VPL.` A call indicating lamp is thereupon lit,up`at the operators position The operator plugs into the seized jack. She thereby transmits a signal to the repeater Ueli. for example inthe form of potential of one of the speaking leads. 'I'his signal is translated `into an alteri nating current impulse which is `sentback over the `connecting line `VL5 to the repeater Ue. Here it is converted back into a direct current signal which is transmitted to the repeater Ue.

f At `this repeater the direct current signal is conu f tential to the b-lead which influences a relay connected to the b-lead in the repeater Ucl. The result of this influencing' is that by the transitory application of a direct current signal to the clead in the repeater Ucl and impulse is transmitted forward and `passes over vthe connecting line VL@ `to the repeaterl U63 `an alternating current impulse. This alternating current im-l pulse causes switching in the repeater Uet which enables the operator at the position VPL to tranmit selecting impulses back over the line and thereby to complete the connectionl If after initiating the call by operatinga magneto athis station the calling subscriber in the local battery exchange A has remained .athis station and has taken up his receiver asecond impulse is transmitted from the repeater U61 which passing over the connecting line to the operators position VPL operates there a supervisory lamp asa signalthat the calling subscriber is at his" station. The operator can thereupon cornmence to dial and set the selectorsgiving access to subscriber Tnd, namely the firstgroup selector y GWh and the final selector LWb.`

` If,v however, after operating his magneto the calling subscriber has not yet taken up hisr receiver he must'first be called by the operator. For this purpose the operator switches over a so-called ringing switch, this transmits a perma-V `nent direct current signal to the repeater Ueli which is translated intol an alternating current impulse train at this latter repeater which is maintained until the ringing switch'is switched A back' again. This impulse train passes back over ther line VLSto the repeater Ue. Here it is translated into a direct current impulse train and after being converted inthe repeater U63 into an alternating current impulse train' passes as a `direct current impulse train to the repeater Uel. Now it may happen that 'at-the moment at which the ringing current impulse train reaches the repeater Uel from the operator, the 'calling subscriber replies and. accordingly a direct current signal is also transmitted forwardly to the repeater Uel over the connecting path which has been set up. The reply signal from the calling subscriber'now effects a disconnection of the ringing current `receiving relay from the line in the normal way and. in its place connects up a receiving relay which is to receive the selecting impulses transmitted by the operator. Naturally the reply signal also tends to bring about the same switching operation if it is received simultaneously with ringing current impulses from the opera-tor. Thus it may happen that since ringing current impulses and selecting im pulses cannot be differentiated the incoming ringing current impulses operate upon the receiving A relay provided for setting the switches on the to be understood will now be described" with reference to. Fig. 2. -As soon as the call nder'AS and the connecting switch AW have become set on the calling subscribers line after'the latter (subscriber Tal for example) has initiated' a call, potential is connected temporarily to'the fit-lead in the connecting switch AW and thereby relay AI is energized over contact 20ct, winding gondary switch MW to be started up.

The secondary switch'is set in known manner with which the. present invention is not con,-

cerned. When the secondary switch has found l a free line the testing relay PI energizes over the .test wiper cm and the seizing relay of the repeater U62. to rest andr guards the seized line. The seizure is ,extended to the repeater U63 and to the group selector GWG from the repeater U62. Relay PI switches through the speaking leads to the repeater U62 at contacts 2p! and 3p! In addition relay .Pl starts up an auxiliary switch of which only wiper di is shown. The impulses are transmitted automatically over this wiper and set the switches fGWe in the exchange C and GWd in the exchange D. As is indicated in the figure these impulses are transmitted over wiper di in the repeater Uel by the connection of earth po- U62 and from there passes over the blead to the repeater Uel as a direct current impulse. In

-the repeater U62 a repeating relay H2 is energized -temporarily by this impulse. This relay `closes the following circuit for relay El in the repeater Uel: earth, battery, Contact 31112, wiper bm, contact 410|, and 5112i, windingY of relay El and earth. Relay AEl energizes vand energizes relay BI: earth, contacts Zlpl and 226i, winding .of relay Bi, battery and earth. Relay BI locks up over contact 23111 independently of relay E! which releases after a short time. After relay El `has released the following circuit is completed `for relay NI: earth, contacts lcl, l26l, lbl and Bfl., .winding of relay Nl, contacts Illml and l Inl, resistance` Wi, Abattery and earth. Relay NI energizes and connects earth to the a-lead over itscontact 'inl and the closed contact lpl. This earth potential operates as van impulse on the repeater U e2 and is transmitted over the line VL tothe repeater U63 and switches over its repeater Yso that impulses transmitted from the operatorsfposition VPL can be received. The

connection of 4earth potential to the a-lead over contact 'Inl is terminatedl by relay Ml energizing .in series with relay Nl after the opening of conn tact Hal. Relay MI short-circuits relay Nl over contact Qml and relay Ni releases and terminates the` impulse transmitted to the repeater U62. Relay 'Ml locks up over itscontact Sml in the circuit: earth, contacts I3cl, I2el, and 51ml, winding of relay MI, resistance Wi, battery and earth.v 1

After the release,y of relay Nl relay Dr is convnectedtothe a-lead which leads to the connecting switch AW over contacts 38ml, 3911.1 and 3llc'l. In thisswitch a relay which is not shown is con- It is here This brings the secondary switch fifi nected to earth and this relay causesfthe speaking leads to be switched through to the calling subscriber. Relay Dr energizes in the above- `mentioned circuit and closes contact lIIldr.

'If the waiting subscriber has remained athis station, relay `Y `energizes in the repeater HUeI over the loop closedwhenthe receiver is taken up: potential on the a-lead, the calling subscribers loop, the b-lead, contact 32 f I, the Winding of relay Y and earth. Relay Y energizes and short circuits relay MI over earth, contacts My and 422i. Relay `MI releases. Relay ZI now 1energizes in the following circuit: earth, con- `tacts My and I'ImI, winding of relay ZI, battery and earth. Relay ZI locks up independently "of contact I'ImI overits Contact I5zl. After relay MI has released relay NI energizes again over earth, contacts I3cl, I2eI, IBbI, BfI, `the winding of relay NI, IIJmI and I IhI, resistance Wi,` battery and earthy` Relay NI transmits another short impulse over contactzlnl to the repeater Ue2 over the a.-lead. This impulse is extended to the operators position VPL after corresponding conversationAt theoperators position a `supervisory lamp is operated indicating that the` 1 calling subscriber `has replied. `At the same time the transmission of ringing current impulses lfrom the operators position is prevented. The `impulse is terminated in the repeater UeI through relay MI energizing in series with relay NI after the opening of contact IInI. Relay Ml short-circuits relay NI `whereupon the latter releaseswhile` the former holds up.

After relaysZI and MI have energized l. the following circuit is set up `for relay XI: earth, contacts 28cI, 26ml, 252|, the winding of relay XI, battery and earth. Relay XI locks up over its contact ZllrI independently of relay ZI. RelayXI by opening its contact 5:rI disconnects relay EI fromv thea-lead and in its place connectsthe impulse receiving relay J I over con- When the operatoritransmits impulses from the exchange position VPL for setting the switch on the desired subscribers line relay` H2 is again energized impulsively in the repeater UeZ, this relaygcompleting the following circuit for relay J I earth, battery, contact31h2, wiperbm, `contacts lipI and 5ml, the winding of relay J I` and earth. The iirst `impulse energizes a relayQI i `which is not shown andwhich seizes the group selector C-rWbover contact 36e/I and lead c. The

" impulses are `transmitted over earth, contact `357I `and the a-lead to the impulse receiving re# The exchange operator `must accordingly ring` the subscriber.` She therefore throws `over `her ringing key and thus transmits impulses `tothe repeater UeI so long asthe ringing switch is operated. These impulses again impulsively energize relay H2 in the repeater U32. Relay EI Relay FI energizes and being slow to release holds up throughout the ringing impulses. `Relay MI also holds up in the same way in spite of contact I2e|1` temporarily breaking the locking circuit for relay MI at each impulse. A constant `potential isapplied to the b--lead to the connection switch AW over a choke-coil`SL `and con-` tact 3IfI and causes a source of ringing current to be connected to the calling line at this switch.

At the end o-f the ringing impulse relay EI nally releases. Relay FI releasesin consequence. When now the calling subscriber replies potential is applied to the b-lead from the connecting switch' AW in response to which relay Y in the repeater UeI energizes. Relay Y short-circuits relay MI at contact Illy and relay MI releases. Relay NI can now energize and applies a temporary earth to the a-lead over its `contact lul.` An impulse isthus transmitted `to the operators position VPL indicating tothe operator that the calling subscriberhas replied. At `the same time the transmission of Iringing current from theoperator` is prevented byfthis impulse. The impulse is terminated by theenergizing of relay MI During the release of relay MI relay Dr holds up over contact l8r/I and the a-lead tothe connecting switch. l

After relay MI has `released relay ZI energizes again over earth, contacts Illy and I'ImI, the

" Winding of `relay ZI, battery and earth. Relay `XI is then operated over contacts 252| and 261m.

At Contact 5ml relay XI disconnects the ringing receiving relay E'I from the b-lead and over contact GxI `connects up the impulse receiving relay J I in its place. `The operator can now i subscriber simultaneously. Now irrespective of the time atwhich the two signals `reach there- `peater relay El must be prevented from being prematurely `disconnected by relay Y and relay i J IA from being connected to the b-lead in its `place because the ringing impulses,` which just asjthe selecting impulses, are transmitted by the application of potential to the `b-lead over contact 3`Ih2 in the repeater UcZ, must be prevented from inuencing the `impulse receiving relay J I. Otherwise this would result in a false setting of the switches.

i The undesirable event of the simultaneous reception `of both signals occurif the first ringing impulse from the operators position VPL arrivesr at the'imoment at which the earth impulse `produced by the reply signal of the calling subl scriber is transmitted `over contact Inl and the b-lead. When this occurs relay Y has been energized by the calling subscribers relay signal and'relay MI releases thereby connecting up relays ZI `and NI simultaneously. Since relay MI, which is slow to4 energize, `has not yet ener" gized `relay XI cannot yet energize over contact 26ml in this `case and no switching over ofthe b-lead from relay El to relay JI cantake place. When now relay E?! is energized by the iirst ringingimpulse the circuit for relay NI and for relay MI disposed in series with' it is immediately broken by the opening of contact I2eI. Relay `NI releases again and relay M'I is not energized again; Relay FI becomes energized by relay EI over` contact IeI. Relay FI breaks a` further point in the circuit `fo-r relays NI and MI at contact BfI. Relay FI being slowto release holds up during theringing impulse. Relay Y is disconnected frorn'the b-lead by contact 32fI. Relay Y releasesagainA andtrelay ZI holds `up over earth, contacts Icl, -lal, :limi and tgl, the winding of -relay Zi battery and earth. Dun` ing `the release of relays Nl and lYi lrelay Dr is held energized in the `following circuit: earth, contacts 4310i, Mfl, winding II of -relay Dr, contact Mdr, battery and earth.

At the end of the ringing impulses relay El releases nally and relay Fl deenergizes in consequence. Since the calling subscriber is still `at his ystation relay Y energizes again over contact 32fl. After relays El and FI have released relay Ni also energizes again. Over contact In! relay Nl transmitsa short reply impulse over the a-lead to the `repeater U62v whence it is extended to the Loperators position. After the opening of contact Ilnl relay MI energizes again in series with relay Nl. Relayk .Xi now energizes again over earth, contactsiZcl, 26ml and 252i, the winding of relay XI, 'battery and earth. Relay Xl energizes and locks up independently of relay ZI. Relay XI disconnects relay El from the b-lead and connects relay J l in place of it.

`Theoperator now sends back impulses which i cause the vswitches to be set in the wanted subscribers lline through the intermediary of relay Jil. f v

In the case in which, when the two signals are received simultaneously, the earth impulse transmitted by the reply signal of thelcalling subscriber has already been transmitted over `contact Inl and the a-lead, i. e., if relay lVII has alreadylenergized in series with relay Nl ringing impulses can no longer be transmitted back by the operator because the subscribers reply impulse has already been received at the operators positionA andthe transmission of the ringing current is prevented sothat the switching over of the ringing key Yby the operator is rendered inoperative.

Release takes place either automatically after the expiry of given time, or in response rto the calling subscriber replacing his receiver. `Relay Yin the repeater thereupon release and relay AI is short-circuited and deenergizes whereupon relay Cl also releases and in consequence al1-the other relays.

I claim:

1. Signalling apparatus for use in a telephone system comprising, a line, a relay normally connected to said line and responsive to signalling in one direction thereover, a relay normally disconnected from said line, and means responsive to signalling in the opposite direction over said line for causing said first relay to be disconnect-v v other device connected to the trunk and actuated thereover by the operator for causing the subscriber to be signalled, a third device connected to the trunk and actuated thereover by the subscriber for causing the second device' to be disconnected from the trunk and the first device to be connected tothe trunk, said rst device. then controllable byv the operator to direct the Vextension of .said branch connection, and

.means controlled jointlyby the second and third -device and effective, responsive to actuation of `the second device ,by-the `,operator and Aconcurrent actuation `of. the third device by the subscriber, tocause the actuation of the third device to be rendered effective to cause the second device to be disconnected from the trunk and the first device to be connected thereto only upon termination of the actuation of the second device.

3. In a telephone system, a subscribers station and a line therefor, an operators position, a trunk line, means for completing la connection between the subscribers line and the operators position over the trunk line, means for extending a branch connection from said llast connection, a control device for said last means, another device connected to the trunk and actuated thereover by the operator for causing the subscriber to be signalled, a third device connected to the trunk and actuated thereover bythe subscriber for signalling the operators positionto f prevent actuation of the second device by the operator and for causing the second device to bey disconnected from the trunk and the rstfdevice to beconnected to the trunk substantially simultaneously with the termination` of said signalling,

said rst device then controllable by the opera-g tor to direct the extension of said branch connection, and means controlled jointly Vby the second and third devices and effective responsive to the concurrent actuation thereof for causing said signalling to be interrupted and the actuation of the third device to be rendered eective only.

4.A In a signal receiving devicefor use in a telephone system, a plurality of lines'terminating in the device, signal receiving means normally connected to one of said lines, signal receiving means normally disconnected from said one line, and means connected to another of said lines and operable thereover both to 'cause an impulse of current to be transmitted over said one Vline thereby to promote the blocking of signalling to saiddevice over said one line and also to cause said first means to be disconnected fromsaid one line and said second means to be connected to said one line substantially simultaneously with the cessation of the transmission of said impulse, said first means effective, if actuated over said one line before the transmission thereover of said impulse, to render the operation of said last means ineffective for so long as the actuation persists.

5. In a signal receiving device for use in a telephone system,'a plurality of lines `terminating in the device, signal receiving means normally connected to one of said lines, signal receiving means normally disconnected from said one line, and means connected to another of said lines and operable thereover both to cause an impulse of f impulse, said first means effective, if actuated` over said one line during the transmission thereover of said impulse, to cause .the impulse to be interrupted and said last means to be rendered ineffective for so long as the actuation persists, said last means then effective upon subsequent deactuation of said rst means to cause the im? pulse of current to be transmitted and to cause said iirst means to be disconnected from said one line and said second means connected thereto.

6l Signalling apparatus for use in a telephone a' system comprising, a line, a relay connected to` the line and responsive only to signalling current transmitted thereover in one direction, a second 'relay connected to said line and responsive only to signalling current transmitted thereover in the opposite direction, a third relay, a fourth relay for disconnecting the second relay` from the line` l,the line and responsive only to signalling current transmitted thereover in one direction, a secondl relay connected to said line andk responsive only to signalling current transmitted thereover in the opposite direction, a third relay, a fourth relay for disconnecting the second relay fromthe line and for connecting the third relay to said line to respond to signalling current transe" interval, said circuit effective if signalling curmitted thereover in said opposite direction, and acircuit controlled jointly by the flrst and second relays for actuating the fourth relay a predetermined interval of time after the receipt of i signalling current transmitted In said one direction unless signalling current transmittedl to theopposite direction is received during that time rent transmitted in the opposite direction is received during that time interval tocause the fourth relay to be actuated a predetermined time interval after the cessation of the transmission of current in the opposite direction.

8. In combination, three relays, acircuit controlled by two of the relays for energizing the third relay when said two relays are energized together, a circuit controlled by .one of the two relays for initially energizing `the second of the two relays when the first relay is deenergizeda circuit for energizing the rst relay, an incomplete shunt circuit about the rst relay prepared by the second relay when `deenergized, and means for completing the shunt circuit to deenergize the first relay and thereby cause the second relay to be energized over the second circuit, the second relay thereupon effective to complete a locling circuit for itself and t'o openthe shunt circuit, said iirst relay then effective to reenergize over said third circuit to cooperate with the second relay in causing the third relay to be energized over the first circuit.

9. Signalling apparatus iorvuse in telephone or like systems, comprising, a line, a relay, means responsive to signalling over said line in one direction for conditioning said relay to receive signals subsequently transmitted over the line in the opposite direction, and means responsive to signalling over said line in said opposite direction prior to the conditioning of said relay `for rendering said rst means ineffectivelfor so long said signalling in said opposite direction persists. l

l0. Signalling apparatus `for use 1n telephone or like systems, comprising, tWo signalling circuits, a relay, means responsive to signalling over one oil said circuits for conditioning said relay a to receive signals subsequently transmitted over i the other one of said circuits, and` means respon- `sive to signalling over said other circuit prior to said conditioning of said relay for` rendering said rst meansineffective `for so long as said signalling over said other circuit persists.

ll. Signalling apparatus for use in telephone or like systems, comprising, a line, ar signalreceiving device, means for both transmitting a transitory signal over the line in one direction to promote blocking `of signalling over the line in the opposite direction and, substantially simultaneously With the termination of the transmis-` sion of` said transitory signal, conditioning said device to respond to `signalling over the line in said opposite direction, and means responsive to signalling over the line in said opposite direction before the transmission of said transitory signal thereover for rendering said rst means ineiective for so long as said signalling in said opposite direction persists.

12. Signalling `apparatus for use in `telephone or like systems, comprising, a line, a signal receiving device, means `for both transmitting a transitory `signal over the linein one direction to promote blocking of signalling over the line in the opposite direction and, substantially simul` taneously with the termination of the transmis# sion of said transitory signal,` conditioning said device to respond to signalling over the line in said opposite direction, and means responsive to signalling .over the line in said opposite direction 4 `EDUARD WOCHINGER.` 

